When working in confined spaces, such as when a dentist is performing an intra-oral procedure on a patient, there is often a need for both optics and fluid. In such circumstances the optical component often takes the form of light being provided through an optical fiber to illuminate the work area. Likewise, the fluid component often is in the form of pressurized air or liquid, but also could be in the form of a fluid under a negative pressure such as a vacuum. The present invention relates to bundled conduits for accurately delivering optics and for carrying fluid to, or delivering fluid from the combined ends of the conduits.
The problems that the present invention addresses arise in many different fields of technology. However, they are described herein with respect to only a few of those fields, and primarily with respect to dental tools such as handpieces. Many conventional dental handpieces such as rotary tools used for drilling, cleaning and polishing include so-called chip-air and water. The air and water typically are provided to the handpiece from an external source and are fed into the proximal end of the tool through an appropriate industry standard coupling. Although there are many different configurations for routing chip air and water through the handpiece, a typical structure has, within the tool, separate fluid conduits extending from the coupling through the body of the tool, terminating at one or more orifices at the working, or distal end of the tool. The chip air and water are preferably aimed at or near the working end of the tool, for instance a burr, and are used to assist the dentist. When the dentist is drilling a tooth dust and or other particles are inevitably created. With a handpiece that provides chip air and water, the dentist may clean the working surface with either air or water, or both. Air and water may also be used to cool the working area.
Likewise, many known dental tools include equipment to deliver light through the distal end of the tool and onto the working surface of the tooth. While nearly all dentists use overhead lights to illuminate their patient's teeth, shadows caused by the dentist and tools and the like are always a problem. Light directed into the intra-oral area through the dental appliance helps alleviate the problems caused by shadow. As with chip air and water, there are many different known methods to deliver light through a handpiece. Typical among these methods include the use of fiber optic strands extending through the handpiece, and light emitting elements positioned near the distal end of the handpiece.
One example of the former technique is exemplified in U.S. Pat. No. 6,149,430, which is directed to a molded handpiece. During the molding process conduits for chip air, water and a light valve may be formed according to certain specified lost material casting processes. An example of the later is disclosed in U.S. Pat. No. 4,648,838. The handpiece described in the '838 includes a light emitting element positioned within the distal end of the canula in a position to cast light on the intra-oral region where the dentist is working. In an alternative embodiment, the light emitting element is positioned relatively more remotely from the distal end of the tool and light is transmitted to the distal end through a fiber optic bundle. As with the apparatus described in the '430 patent, the canula described in the '838 patent includes separate passageways for carrying air and water from an external source through the handpiece and to the working end of the tool.
Another known, and perhaps more typical method of delivering fluid and light through a handpiece is with standard metal (e.g. stainless steel) handpieces that have a hollow handle. In tools such as these the chip air and water may be delivered through dedicated tubing that may be suspended in the handle along a substantial length thereof between the standard coupling at the proximate end and an orifice at the distal end. Likewise, light may be provided through a fiber optic bundle that is separately routed through the handle. Like the fluid tubes, the fiber optic bundle is often suspended between the ends. In some handpieces the optical fiber bundle is bifurcated near the working end of the handpiece to provide light directed on the working tool (such as a burr) from two different angles.
Each of the handpieces disclosed in the '430 and '838 patents, and the hollow handpieces described above, represents an improvement over the art. However, each has certain disadvantages with respect to the method of delivering fluid and light to the working end of the tool.
With respect to the molded handpiece described in the '430 patent it is necessary to set the fluid-carrying conduits into the handle by including either pre-formed tubes in the mold, or as described in the patent, including in the mold fusible material that is to be removed after the handpiece has been formed. With either approach it has been found that there are several problems. Chief among these is achieving the proper “aim” for the fluid and light that is emitted out of the orifices at the working end of the tool. Thus, during the molding process the fluid tubes and the light valve (for example, fiber optic bundle) are subject to movement relative to one another and relative to the mold boundaries as the liquefied polymer is injected into the mold and during the curing process. Such movement causes relative misalignment in the direction that the orifices are aimed. Furthermore, as noted in the patent, there are limitations on the minimum diameter of a conduit formed by the lost material casting process used in the patent. When it comes to casting in the chip air and water conduits, and conduit for carrying an optical fiber, the size of the handpiece may be increased to the point where the tool is larger than dentists want to use.
With respect to the '838 patent there are the obvious limitations that are present when a light emitting element (such as an LED) are used. Although most LEDs have a relatively long life, not all light transmitted from the element will reach the area of interest. Moreover, dental tools must be sterilized before use. This is typically done in an autoclave, and the operating temperatures and pressures in an autoclave may damage an LED.
Finally, as to tubular metal handpieces, there are often problems with maintaining fluid-tight plumbing fittings that result from the high frequency vibrations caused by rotary bits that may rotate at speeds upward of 300,000 rpm. Furthermore, when a hollow handpiece is autoclaved, the internal areas of the handpiece are exposed to approximately the same temperatures as the outside. Such high temperatures over repeated cleaning cycles can severely damage the optical transmission properties of fiber optics. In contrast, with a molded handpiece such as that described in the '430 patent that has a relatively more solid handle, the internal temperature of the handle body is relatively less than the temperature of the surface during autoclaving.
A problem that is common to each of the prior art devices discussed above relates not to the structural or functional attributes of the devices, but rather to the cost. With each the handpieces noted above the manufacturing and assembly costs relating to the delivery of light and fluid to the working end of the tool is significant. As an example, with a bifurcated optical fiber light delivery system as described above, assembly of the handpiece is quite difficult since the optical fibers must be routed through the handpiece and into separate openings near the head of the unit. Routing the fibers through the handpiece is difficult enough. Placing the fibers in the correct position through the openings is much more difficult. As a result, the way that light and fluid are delivered adds a significant cost element to these units. Likewise, with a molded handpiece that routes fluid and light delivery tubes through separately molded-in apertures, it is time consuming and expensive to first correctly place in the tool the fusible material that will eventually define the apertures, then after molding, to correctly route optical fibers and the like.
There is a need, therefore, for a more efficient and efficacious structure for delivering fluid and light to the working end of a dental tool or other instrument.